Connecting rod with strap type cap



July 2, 1968 I c. N. FANGMAN 3,390,925

CONNECTING ROD WITH STRAP TYPE CAP Filed April 19, 1966 a Sheets-Sheet 1"h :3 341-,33 E3 H 3 J IQJ"? "T "If" a? H I! INVENTOR. CharlesN.Fangma;n BY I) 2 .J WK

ATTORNEYS July 2, 1968 c. N. FANGMAN 3,390,925

CONNECTING ROD WITH STRAP TYPE CAP 5 Sheets-Sheet 2 Filed April 19, 1966I 43 E15 5 42' BE 44- INVENTOR.

Charles N. Fangman FLZIIIIIIIIIIIII BY ATTORNEYS July 2, 1968 c. N.FANGMAN 3,390,925

- CONNECTING ROD WITH STRAP TYPE CAP Filed April 19, 1966 3 Sheets-SheetFIT-E E g El 5 .7

YINVENTOR.

CHARLES N. FAmmn BY a l dnmvs United States Patent 3,390,925 CONNECTINGROD WITH STRAP TYPE CAP Charles N. Fangman, Peoria, 111., assignor toCaterpillar Tractor Co., Peoria, 111., a corporation of CaliforniaContinuation-impart of application Ser. No. 262,946,

Mar. 5, 1963. This application Apr. 19, 1966, Ser.

2 Claims. (Cl. 308-15) ABSTRACT OF THE DISCLOSURE A connecting rodbearing assembly is provided with a flexible strap type bearing caphaving a decreasing cross section toward the center thereof for applyingevenly distributed pressure to a lower bearing half shell disposedtherein; the assembly is further provided with tab and notch means foraccurately aligning and locking both the bearing half shells and forlocating the strap in a fixed transverse position on the connecting rod.

This application is a continuation-in-part of my assignees United StatesSer. No. 262,946 filed Mar. 5, 1963, now abandoned.

This invention relates to connecting rod bearings and particularly to aflexible strap type bearing cap which has a varying cross sectionthroughout its lower half.

High cylinder pressures in high performance engines require largebearing areas for the connecting rod big end bearings. This requirementhas led to large connecting rods and related bearing cap constructionswhich prevent removal of the pistons from the engine through the top ofthe block, in the preferred method of disassembling the pistons from theengine. It is an important object of the present invention to keep thebig end bearing portion of the connecting rod small enough to permitremoval of the piston through the top of the block.

As the bearing areas have been enlarged the weight and mass of theconnecting rod and bearing cap assembly have increased. The resultingincrease in the inertial loads on the connecting rods becomesparticularly significant in four cycle engines during the exhauststroke. A conventional, rigid connecting rod cap, when machined true andassembled to the crankshaft journal with proper clearance, is limited inthe effective bearing area which can be presented to the matingcylindrical surfaces between the rod bearing'and journal. The limitationon the effective bearing surface is in the order of approximately 40 ofthese mating surfaces. It is another object of the present invention tomake the connecting cap in the form of a flexible strap which canprovide substantially 180 of bearing contact surface between the rod andthe crankshaft hearing.

In accordance with the present invention the flexible strap has a crosssection that varies from a minimum-at the center to a maximum at the endportions of the strap which are engaged with the bearing shell. Theflexible strap of the present invention distributes the moment ofinertia proportional to the bending moment applied during spreading ofthe strap in assembly and disassembly and as a result of inertial loadsdeveloped during operation. As a result, the strap opens evenly andprevents concentration of a moment arm to eliminate the possibility ofputting a permanent set in the strap at any one weak point. Also, as thestrap is secured to the rod and drawn upward into .operative associationwith the bearing shell and journal, pressure is distributed evenly aboutthe circumference of the bearing shell to provide the substantially 180of bearing contact mentioned above. The increased contact area incombination with the substantially uniform distribution .of the contactpressure permits the contact pressure to be significantly decreased incomparison to conventional connecting rod bearing cap assemblies nowknown. The strap of the present invention therefore substantiallyincreases the bearing life. A flexible strap having this constructionand effective to function in the manner described constitutes a furtherobject of the present invention.

According to a modified construction .of the invention, the upstandingend portions of the flexible strap are of greater lateral extent thanthe big end bearing portion. Such a modified construction provides astrap that can be assembled and disassembled without the use of specialtools since the upstanding ends will tend to spring open when the meansfor retaining the strap on the big end bearing portion are released.

Other and further objects of the present invention will be apparent fromthe following description and claims and are illustrated in theaccompanying drawings which, by way of illustration, show preferredembodiments of the present invention and the principles thereof and whatis now considered to be the best mode contemplated for applying theseprinciples. Other embodiments of the invention embodying the same orequivalent principles may be used and structural changes may be made asdesired by those skilled in the art without departing from the presentinvention and the purview of the appended claims.

In the drawings:

FIG. 1 is an elevation view, partly broken away in section to showdetails of construction, of a connecting rod and strap type bearing capassembly constructed in accordance with one embodiment of the presentinvention;

FIG. 2 is an end elevation view of the connecting rod and bearing capassembly shown in FIG. 1;

FIG. 3 is an elevation view, partly broken away in section to showdetails .of construction, of a connecting rod andstrap type bearing capassembly constructed in accordance with another embodiment of thepresent invention;

FIG. 4 is an end elevation view of the connecting rod and bearing capassembly shown in FIG. 3;

FIG. 5 is a fragmentary enlarged view in section of the portion of thebearing shown encircled by the arrows 55 in FIG. 3;

FIG. 6 is an elevation view, partly broken away in section to showdetails of construction, of a connecting rod and strap type bearing capassembly constructed in accordance with still another embodiment of thepresent invention; and,

FIG. 7 is a cross-sectional view taken on the line VII-VII of FIG. 6.

In FIGS. 1 and 2 a bearing constructed in accordance with one embodimentof the present invention is indicated generally by the reference numeral11. The bearing 11 comprises a connecting rod 12 having a big endbearing portion 13 in which an upper bearing half shell 14 is disposedfor engagement with the upper surface of the crankshaft journal I.

A bearing cap 16 holds a lower bearing half shell 17 in position againstthe lower surface of the journal I. In the form of the inventionillustrated in FIGS. 1 and 2 the bearing half shells 14 and 17 may, ifdesired, be bonded to the connecting rod and strap by epoxy resin.

In accordance with the present invention the bearing cap 16 is formed asa flexible strap type cap to exert a substantially uniform pressureabout the entire of the journal I encompassed by the lower bearing shell17. As will be described in greater detail below, this uniformdistribution of pressure is achieved through the variation in the crosssection between the lowermost, center portion of the strap 16, indicatedby the line AA, and the portion adjacent the uppermost end of thebearing shell 17, indicated by the line BB in FIG. 1. The strap 16includes upstanding end portions 19 which extend alongside the big endbearing portion 13 of the connecting rod. The ends 19 are each formedwith a bolt hole 21 which is somewhat oversized to accommodate assemblyand the slight vertical movement produced in the strap during assembly.The big end bearing portion 13 is likewise formed with a bolt hole 22. Atie bolt 23 having a bolt head 24 and a nut 26 and Washer 27 received inrecesses formed in the ends 19 is passed through the strap andconnecting rod to clamp the strap in the position illustrated.

Each of the upstanding ends 19 have a slot 31, best shown in FIG. 2, forreception of the dowel pin 32. The dowel pins maintain the strap in afixed position transversely of the connecting rod. The dowel pins arepreferably mounted in line in the big end bearing portion 13 and nearone end surface thereof so that the strap 16 is always assembled to theconnecting rod in the same manner.

Each of the upstanding ends 19 are formed with inclined surfaces 33which mate with correspondingly inclined surfaces 34 on the big endbearing portion 13 of the connecting rod. The engagement of theseinclined surfaces during tightening of the tie bolt 23 produces asliding ramp effect which lifts the strap 16 and presses the bearingshell 17 into engagement with the lower surface of the journal I.

The strap type cap of the present invention offers a significant weightreduction as compared to conventional, rigid connecting rod bearingcaps. This flexible strap in combination with the manner in which it isattached to the connecting rod by the tie bolt 23 permits the big endbearing portion 13 of the connecting rod to be kept sufliciently smallthat it can pass through the cylinder in the engine block. Also, theweight saving realized by this construction reduces the inertia loadingduring the exhaust stroke of operation of a four cycle engine.

The above described variations in the cross section of the strap betweenlocations AA and BB serves an important function. This variation incross section distributes the moment of inertia of the bearing shellengaging portion of the strap in a manner such that the cross sectionincreases in accordance with the increase in bending moment about thisbearing engaging portion of the strap during spreading of the strap onassembly or disassembly. As a result, the strap opens evenly and thepossibility of putting a permanent set in the strap at any one weakpoint is eliminated.

This distribution of the moment of inertia in the bearing shell engagingportion of the strap produces a substantially uniform pressure orbearing crush on the bearing shell when the strap is clamped in positionon the big end bearing portion 13 by the action of the tie bolt 23 andinclined mating surfaces 33 and 34. The strap and bearing shell 17conform to the lower surface of the journal I to provide substantially180 of surface contact. inertial loads are thus distributed in a uniformmanner over a large area to substantially increase bearing life.

In FIGS. 3 through a bearing constructed in accordance with anotherembodiment of the present invention is indicated generally by thereference numeral 41. The bearing 41 incorporates a tab construction,best seen in FIGS. 4 and 5, which affords means both for locating orlocking the bearing in fixed transverse position in the strap and on theconnecting rod and for locating the strap in fixed transverse positionon the connecting rod.

The lower bearing shell 17 is formed with an outwardly projecting tab 42which is received in vertically aligned notches 44 and 43 in the strap16 and big end portion 13, respectively. In this instance the lowermostedges 13E, see FIG. 4, extend downwardly beyond the center line of thecrankshaft pin and juncture of the upper and lower beariug shells bydistance X as indicated in FIG. 5 to enable 1 the tab 42 to locate thestrap transversely as described.

The upper bearing shell 14 also includes a tab 46 which is inserted in anotch 47 in the big end portion 13 of the connecting rod. The tab 46 isnot received within a corresponding notch in the bearing strap sinceengagement of tab 42 with the side walls of notch 44 is sufficient tomaintain alignment of the strap with respect to the big end portion 13.

The above described bearing tab and notch construction insures alignmentwithout auxiliary dowel pins such as pins 32 in the FIG. 1 form of theinvention.

The tabs are formed in pairs and are preferably offset as illustrated inFIG. 4 to insure that the bearings and strap were not reversed on therod during assembly and disassembly.

In FIGS. 6 and 7 another embodiment of the invention is shown whereinthe strap 16a has been forged and machined such that in a relaxed orunassembled state the upstanding end portions 1% thereof are spread openand are free from engagement with the big end bearing portion 13. Whenassembled to the rod 12, the ends 19a are drawn together by the bolt23a. The ramps 33a and 34a function in the same manner as thosepreviously described with respect to FIG. 1. As best shown in FIG. 7,the embodiment of FIG. 6 has been provided with a slot 50 and tang 52connection which maintains the strap in a fixed position transversely ofthe connecting rod.

The modified construction of FIGS. 6 and 7 is especially advantageous inthat it provides a strap Which can be assembled and disassembled withoutthe use of special tools. Inasmuch as the strap has a spring-likeaction, it will open automatically to the spread position of FIG. 6 whenthe retaining bolt 23a is loosened. The variation in cross sectionbetween the lowermost, center portion of the strap 16:: and the portionthereof adjacent the uppermost end of the bearing shell 17, which causesthe strap to close evenly around the lower periphery of the crankshaftjournal, is particularly beneficial in this embodiment.

Hence, while I have illustrated and described the preferred embodimentsof my invention, it is to be understood that these are capable ofvariation and modification, and I therefore do not wish to be limited tothe precise details set forth, but desire to avail myself of suchchanges and alterations as fall within the purview of the followingclaims.

I claim:

1. In a connecting rod bearing assembly the combination comprising:

(a) a connecting rod having a big end bearing portion in which an upperbearing half shell is disposed for engagement with the upper surface ofa crankshaft journal;

(b) a flexible strap type cap in which a lower bearing half shell isdisposed for engagement with the lower surface of said crankshaftjournal;

(c) said flexible strap having a cross section which decreases towardthe center and also having upstanding end portions which, in a relaxedstate, tend to assume a position free from engagement with said big endbearing portion;

(d) a tie belt which passes through the ends of the flexible strap andbig end bearing portion to clamp the strap to the connecting rod;

(e) said upper and lower bearing shells having tab means respectivelyreceived in notch means located on said big end bearing portion and saidflexible strap and effective to maintain transverse alignment of saidbearing shells with respect to said big end bearing portion and saidflexible strap, and at least one of said tab means extending into notchmeans located on both said big end bearing portion and said flexiblestrap for locating the strap in fixed tranverse position on theconnecting rod.

2. In a connecting rod bearing assembly the combination comprising:

(a) a connecting rod having a big end bearing portion in which an upperbearing half shell is disposed for engagement with the upper surface ofa crankshaft journal;

(b) a flexible strap type cap in which a lower bearing half shell isdisposed for engagement with the lower surface of said crankshaftjournal;

(c) said flexible strap having a cross section which decreases towardthe center and also having upstanding end portions which, in a relaxedstate, tend to assume a position free from engagement with said big endbearing portion;

(d) a tie bolt which passes through the ends of the flexible strap andbig end bearing portion to clamp the strap to the connecting rod;

(e) mating inclined surfaces formed on both the upstanding end portionsof said flexible strap and the big end bearing portion for lifting theupstanding ends of the strap on tightening of the tie bolt to press saidupper and lower bearing half shells into contact with the journal underan evenly distributed pressure;

(f) said upper bearing half shell having a first tab means which isreceived in first notch means on said big end bearing portion forlocating and accurately aligning said upper bearing half shell withinsaid big end bearing portion;

(g) said lower bearing half shell having second tab means which arereceived in both a second notch means formed on said flexible strap anda third notch means formed on said big end bearing portion in verticalalignment with said second notch means, said second tab means and secondand third notch means providing means both for locating and locking saidlower bearing half shell in fixed transverse position in the strap andwith respect to said big end bearing portion and for locating the strapin fixed transverse position on the connecting rod.

References Cited UNITED STATES PATENTS 798,505 8/1905 Gordon 287-5202830,791 9/1906 Kirchhoff 287-5202 1,009,244 11/1911 Hartsough 308-671,130,982 3/1915 Kinkead 308-67 1,605,742 11/1926 Jordan 308-2371,872,600 8/1932 Manning 308-237 1,948,176 2/1934 Hopkins 308-2372,124,803 7/1938 Wollner 64-17 2,132,816 10/1938 Wollner 64-17 2,428,60210/ 1947 Yingling 308-67 X 2,639,955 5/1953 Tryon 308-237 2,741,9334/1956 Seitz 74-579 2,890,598 6/1959 Bensinger 74-579 FOREIGN PATENTS653,273 12/ 1935 Germany.

731,730 6/1955 Great Britain.

MARTIN P. SCHWADRON, Primary Examiner.

L. L. JOHNSON, Assistant Examiner.

